Image data transfer system, transmitter circuit and receiver circuit

ABSTRACT

An image data transfer system includes a receiver and a transmitter configured to sequentially receive compressed image data and sequentially transmit transmission data corresponding to the compressed image data to the receiver. The transmitter is configured to, in transmitting a specific transmission data, perform data comparison of bits of a compressed image body data of a specific compressed image data with bits of a previous transmission data transmitted over signal lines allocated to the compressed image body data, incorporate the compressed image body data of the specific compressed image data or the bit-inverted data corresponding thereto into the specific transmission data, in response to the result of the data comparison, and incorporate the compression code of the specific compressed image data into the specific transmission data independently of the result of the data comparison.

CROSS REFERENCE

This application claims priority to Japanese Patent Application No.2016-015549, filed on Jan. 29, 2016, the disclosure of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to an image data transfer system,transmitter circuit and receiver circuit.

BACKGROUND

The power consumption of recent semiconductor integrated circuits tendsto increase more than ever due to their high functionalities. Forexample, recent display panel drivers suffer from a significant increasein the power consumption due to an increase in the number of pixels ofdisplay panels. Power consumption reduction is one of the most importantissues of recent semiconductor integrated circuits.

It is known in the art that, although a semiconductor integrated circuitconsumes power in various ways, a considerable percentage of the powerconsumption in a semiconductor integrated circuit is caused by switchingthe voltage levels on signal lines.

When binary data are transferred over a set of signal lines, the signallines are repeatedly pulled up to the “high” level and pulled down tothe “low” level. In this operation, the signal lines are repeatedlycharged and discharged, and this causes considerable power consumption.

One known technique for reducing the power consumption caused byswitching the voltage levels on the signal lines in transferring binarydata is to transmit a bit-inverted data of a binary data of interest(that is, data obtained by bit-inversion of the bits of the binary dataof interest), when more than half of the bits of the binary data to becurrently transmitted are inverted from the corresponding bits of thepreviously-transferred binary data. Such technique is disclosed, forexample, in Japanese Patent Application Publications Nos. H08-314589 Aand 2009-9289 A.

However, there is room for further reducing the power consumption, whenthe above-described technique is used in transferring compressed imagedata.

SUMMARY

Therefore, an objective of the present disclosure is to provide atechnique for reducing power consumption in transferring compressedimage data. Other objectives and new features of the present disclosurewould be understood by a person skilled in the art from the disclosuregiven below.

In one embodiment, an image data transfer system includes a receiver anda transmitter configured to sequentially receive compressed image dataand sequentially transmit transmission data corresponding to thecompressed image data to the receiver. Each of the compressed image datais generated through a selected compression process selected from aplurality of compression processes and includes a compression codeindicating the selected compression process and a compressed image bodydata. Each of the transmission data includes the compression codeincluded in the corresponding compressed image data and selected one ofthe compressed image body data of the corresponding compressed imagedata and a bit-inverted data obtained through bit-inversion on thecompressed image body data of the corresponding compressed image data.The transmitter is configured to, in transmitting a specific one of thetransmission data corresponding to a specific one of the compressedimage data, perform data comparison of bits of the compressed image bodydata of the specific compressed image data with bits of a previous oneof the transmission data which has just previously transmitted beforethe specific transmission data over signal lines allocated to thecompressed image body data of the specific compressed image data or thebit-inverted data, incorporate the compressed image body data of thespecific compressed image data or the bit-inverted data correspondingthereto into the specific transmission data, in response to the resultof the data comparison, and incorporate the compression code of thespecific compressed image data into the specific transmission dataindependently of the result of the data comparison.

In another embodiment, a transmitter circuit is provided which isconfigured to sequentially receive compressed image data andsequentially transmitting transmission data corresponding to thecompressed image data. Each of the compressed image data is generatedthrough a selected compression process selected from a plurality ofcompression processes and includes a compression code indicating theselected compression process and a compressed image body data. Each ofthe transmission data includes the compression code included in thecorresponding compressed image data and selected one of the compressedimage body data of the corresponding compressed image data and abit-inverted data obtained through bit-inversion on the compressed imagebody data of the corresponding compressed image data. The transmittercircuit includes: a transmission data comparator section configured to,in transmitting a specific one of the transmission data corresponding toa specific one of the compressed image data, perform data comparison ofbits of the compressed image body data of the specific compressed imagedata with bits of a previous one of the transmission data which has justpreviously transmitted before the specific transmission data over signallines allocated to the compressed image body data of the specificcompressed image data or the bit-inverted data corresponding thereto;and a data-bit inversion section configured to incorporate thecompressed image body data of the specific compressed image data or thebit-inverted data corresponding thereto into the specific transmissiondata, in response to the result of the data comparison and incorporatethe compression code of the specific compressed image data into thespecific transmission data independently of the result of the datacomparison.

In still another embodiment, a receiver circuit includes: an interfaceconfigured to externally and sequentially receive transmission datagenerated from compressed image data and inversion indication bitsassociated therewith; and a data-bit inversion section configured tosequentially receive the transmission data and output receptioncompressed image data respectively corresponding to the transmissiondata in response to the inversion indication bits. Each of thecompressed image data is generated through a selected compressionprocess selected from a plurality of compression processes and includesa compression code indicating the selected compression process and acompressed image body data. Each of the transmission data includes thecompression code included in the corresponding compressed image data andselected one of the compressed image body data of the correspondingcompressed image data and a bit-inverted data obtained throughbit-inversion on the compressed image body data of the correspondingcompressed image data. Each of the inversion indication bits indicateswhich of the compressed image body data of the corresponding compressedimage data and the bit-inverted data corresponding thereto is includedin the corresponding transmission data. The data-bit inversion sectionis configured to, in receiving a specific one of the transmission data,refer to the inversion indication bit associated with the specifictransmission data, incorporate the compressed image body data includedin the specific transmission data into the reception compressed imagedata corresponding to the specific transmission data when the specifictransmission data includes the compressed image body data of thespecific compressed image data, incorporate data obtained by performingbit-inversion on the bit-inverted data included in the specifictransmission data into the reception compressed image data correspondingto the specific transmission data, when the specific transmission dataincludes the bit-inversion data of the compressed image body data of thespecific compressed image data, and incorporate the compression codeincluded in the specific transmission data into the reception compressedimage data corresponding to the specific transmission data,independently of the corresponding inversion indication bit.

The present disclosure provides a technique for effectively reducing thepower consumption in transmitting compressed image data.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of the present disclosurewill be more apparent from the following description taken inconjunction with the accompanied drawings, in which:

FIG. 1A is a block diagram illustrating one example of a data transfersystem;

FIG. 1B is a block diagram illustrating one example of a data transfersystem configured to reduce power consumption in data transfer;

FIG. 2 is a diagram schematically illustrating one example of selectionof compression processes with respect to an image;

FIG. 3 is a block diagram illustrating an exemplary configuration of animage data transfer system in one embodiment;

FIG. 4A is a diagram illustrating the format of image data supplied to acompression unit in the present embodiment;

FIG. 4B is a diagram schematically illustrating the format of compressedimage data generated with respect to the respective blocks;

FIG. 5 is a diagram schematically illustrating allocation of signallines in transmitting compressed image data in the image data transfersystem of the present embodiment;

FIG. 6 is a diagram schematically illustrating one example oftransmission of a transmission data in the image data transfer system ofthe present embodiment;

FIG. 7 is a diagram schematically illustrating another example oftransmission of a transmission data in the image data transfer system ofthe present embodiment;

FIG. 8 is a block diagram illustrating an exemplary configuration of animage data transfer system in an embodiment in which the compressioncode length is fixed;

FIG. 9 is a block diagram illustrating an exemplary configuration of adisplay device in which the image data transfer system of the presentembodiment is used to transmit compressed image data within a displaydriver IC; and

FIG. 10 is a block diagram illustrating an exemplary configuration of adisplay device in which the image data transfer system of the presentembodiment is used to transmit compressed image data from a timingcontroller IC to display driver ICs.

DETAILED DESCRIPTION

The disclosure will be now described herein with reference toillustrative embodiments. A person skilled in the art would recognizethat many alternative embodiments can be accomplished using theteachings of the embodiments and that the disclosure is not limited tothe embodiments illustrated for explanatory purposes.

In the following, various embodiments are described with reference tothe attached drawings. It should be noted that same or similar elementsmay be denoted by same or corresponding reference numerals in thefollowing disclosure.

For ease of understanding of the present disclosure, a description isfirst given of power consumption in data transfer and reduction of thepower consumption through data-bit inversion.

FIG. 1A is a block diagram illustrating one example of a data transfersystem 100. A transmitting-side unit 101 and a receiving-side unit 102are connected to each other by a set of signal lines 103. In the exampleillustrated in FIG. 1A, the number of the signal lines 103 is four andthis implies four-bit transmission data are transmitted in parallel.

The data transfer system 100 thus configured may suffer from an increasein power consumption caused by switching of the voltage levels on thesignal lines 103. When data “1111” is transferred just after data “0000”is transferred, for example, the voltage levels are switched on all ofthe signal lines 103 and this undesirably increases the powerconsumption.

One known technique for reducing power consumption caused by datatransfer is to compare a transmission data to be currently transmittedwith that which has been just previously transmitted and transmitbit-inverted data of the transmission data to be currently transmitted,when more than half of the bits are to be inverted. FIG. 1B is a blockdiagram illustrating an exemplary configuration of a data transfersystem 100A which adopts this approach to reduce the power consumption.

In the data transfer system 100A illustrated in FIG. 1B, thetransmitting-side unit 101 and the receiving-side unit 102 are connectedto each other by a set of signal lines 103 a and 103 b. The signal lines103 a are used to transmit transmission data or bit-inverted datathereof and the signal line 103 b is used to transmit an inversionindication bit. The inversion indication bit indicates which of theoriginal transmission data and the bit-inverted data thereof is actuallytransferred over the signal lines 103 a. Most typically, thebit-inverted data is transmitted when more than a half of the bits areto be inverted from the corresponding bits of the data which has beenjust previously transmitted.

When transmitting the bit-inverted data, the transmitting-side unit 101sets the inversion indication bit to “1”, for example, to notify thereceiving-side unit 102 of the fact that the bit-inverted data istransmitted. When identifying that the inversion indication bit is “1”,the receiving-side unit 102 reproduces the original data by invertingthe respective bits of the data transmitted over the signal lines 103 ato output the reproduced data as a reception data. When transmitting theoriginal data without performing bit-inversion, the transmitting-sideunit 101 sets the inversion indication bit to “0”, for example. Whenidentifying that the inversion indication bit is “0”, the receiving-sideunit 102 outputs the data transmitted over the signal lines 103 a as thereception data without change.

When data “1111” is to be transmitted just after data “0000” has beentransmitted, for example, the transmitting-side unit 101 sets theinversion indication bit to “1” and transmits to the receiving-side unit102 a bit-inverted data of the data to be currently transmitted, sinceall the bits of the data to be currently transmitted are inverted fromthe corresponding bits of the data which has been just previouslytransmitted. The receiving-side unit 102 reproduces the original data byinverting the respective bits of the bit-inverted data received from thetransmitting-side unit 101 and outputs the reproduced transmission dataas the reception data. This operation effectively reduces the powerconsumption necessary for data transfer, since the number of the signallines 103 a on which the voltage levels are switched is reduced.

However, the approach illustrated in FIG. 1B may not be suitable fortransmitting compressed image data, which are obtained throughperforming image compression on image data. In the following, adescription is given of transfer of compressed image data.

One of the most typical processes performed on image data is blockcompression, in which image compression is performed in units of blocks.Each block consists of a predetermined number of pixels and is used as aunit of image compression. When block compression is performed, thecompression process applied to each block may be selected on the basisof characteristics of the image data associated with the block. In thiscase, a compression code is described in the compressed image data toindicate the selected compression process.

In some cases, the same compression codes are often described incompressed image data associated with the adjacent blocks, because imagedata associated with adjacent blocks are often compressed with the samecompression process. Therefore, it is possible to reduce the powerconsumption required for transferring compressed image data by makinguse of this fact.

FIG. 2 is a diagram schematically illustrating one example of selectionof image compression processes. In compressing an image data associatedwith each block of an image, a compression process is selected on thebasis of the characteristics of the image data associated with theblock. In the example illustrated in FIG. 2, a compression processidentified by compression code #1 is selected for a block 104 and acompression process identified by compression code #4 is selected forblocks 105 and 106.

Attention should be paid to the fact that image data associated withadjacent blocks often have similar characteristics due to the intrinsicnature of image data, and therefore the same compression process isoften selected in compressing the image data associated with adjacentblocks. This implies that the same compression code is often repeatedlytransmitted when compressed image data associated with adjacent blocksare sequentially transmitted.

Therefore, under such conditions, it is possible to reduce the number ofthe signal lines on which the voltage levels are switched to achievepower consumption reduction, by transmitting compressed image data asfollows:

(1) For the compression code included in a compressed image data, thecompression code is transmitted without performing data-bit inversion.

(2) For the compressed image body data, which is a data including bitsof the compressed image data other than the compression code, thecompressed image body data to be currently transmitted is compared withthe data which has been just previously transmitted, and a selected oneof the compressed image body data and the bit-inverted data thereof istransmitted on the basis of the comparison result.

In a conventional approach in which a selected one of the compressedimage data itself and the bit-inverted data thereof is transmitted forall the bits of the compressed image data, data-bit inversion oftenoccurs for the compression codes, although the compression codes usedfor adjacent blocks are actually same. This is not preferable for powerconsumption reduction. In the present embodiments, power consumption iseffectively reduced in transferring compressed image data by performingthe above-described operations (1) and (2). In the following, adescription is given of a preferred embodiment of an image data transfersystem which performs the above-described operations (1) and (2).

FIG. 3 is a block diagram illustrating an exemplary configuration of animage data transfer system 10 in one embodiment. The image data transfersystem 10 of the present embodiment includes a transmitter circuit 11and a receiver circuit 12. The transmitter circuit 11 and the receivercircuit 12 are connected each other by a set of signal lines 13. Asdescribed later, the signal lines 13 includes signal lines 13 a used fortransmitting a compressed image data 22 and a signal line 13 b used fortransmitting an inversion indication bit 23, which indicates whether ornot data bit inversion is performed in transmitting the compressed imagedata 22. In the following, a data transmitted from the transmittercircuit 11 to the receiver circuit 12 over the signal lines 13 a may bereferred to as a transmission data 24.

The image data transfer system 10 of the present embodiment isconfigured to sequentially receive compressed image data 22 generated byperforming image compression on image data 21 from a compression unit 14and sequentially transfer transmission data 24 corresponding to thecompressed image data 22 from the transmitter circuit 11 to the receivercircuit 12. A dedicated image compression circuit may be used as thecompression unit 14 to generate the compressed image data 22.Alternatively, a processor, such as a CPU (central processing unit), anapplication processor, or a DSP (digital signal processor), may be usedas the compression unit 14.

The compression unit 14 is configured to sequentially generatecompressed image data 22 by performing block compression on image data21 which are sequentially supplied to the compression unit 14. Asdescribed above, block compression is a compression method in whichimage data are compressed in units of blocks defined in the image ofinterest. Each block consists of a predetermined number of pixels.

FIG. 4A illustrates an exemplary format of the image data 21, which aresupplied to the compression unit 14. A plurality of blocks, eachconsisting of a plurality of pixels, are defined in an image. Image data21 associated with the respective blocks are sequentially supplied tothe compression unit 14. For example, image data 21 associated with theblocks in the topmost row of the image are first transmitted in theorder from left to right, and then image data 21 associated with theblocks in the second topmost row of the image are transmitted in theorder from left to right. The same goes for the remaining rows. Imagedata 21 associated with the blocks in the respective rows are suppliedto the compression unit 14 in the order from top to bottom.

When compressing the image data 21 associated with each block, thecompression unit 14 selects a desired compression process from among aplurality of compression processes on the basis of the characteristicsof the image data 21 associated with each block and performs theselected compression process on the image data 21 associated with eachblock to generate the corresponding compressed image data 22. Thisallows using suitable compression processes in accordance with thecharacterization of the image to generate compressed image data 22. Inthe following, the compression process used to generate the compressedimage data 22 associated with a block (that is, the compression processselected to compress the image data 21 associated with the block) isreferred to as the “selected compression process.”

FIG. 4B is a diagram schematically illustrating the formats of thecompressed image data 22 generated for the respective blocks.Illustrated in FIG. 4B are the formats of the compressed image data 22generated through four types of compression processes #1 to #4.

In the present embodiment, the compressed image data 22 associated witheach block is a 64-bit data and includes a compression code and acompressed image body data. The compression code indicates the selectedcompression process used to generate the compressed image data 22associated with each block. The compressed image body data is the partof the compressed image data 22 other than the compression code andincludes information corresponding to the image data 21 associated witheach block.

In the present embodiment, the number of bits of the compression code,which may be hereinafter referred to as “compression code length”, isvariable depending on the selection of the compression processes (thatis, depending on the selected compression process.) In the exampleillustrated in FIG. 4B, the one-bit compression code “0” is assigned tocompression process #1, and the two-bit compression code “10” isassigned to compression process #2. Furthermore, the three-bitcompression code “110” is assigned to compression process #3 and thethree-bit compression code “111” is assigned to compression process #4.In a preferred embodiment, a compression process of a low compressionratio is selected for a low-redundancy image and a compression code witha short compression code length is assigned to the compression processof the low compression ratio, while a compression process of a highcompression ratio is selected for a high-redundancy image and acompression code with a long compression code length is assigned to thecompression process of the high compression ratio. This achieves imagecompression with preferred balancing between suppression of imagequality deterioration and improvement of the compression ratio, evenwhen there is a limitation on the number of bits of the compressed imagedata 22 associated with each block.

It should be noted that the allowed maximum number of bits of thecompression codes and the value (“0” or “1”) of the least significantbit of the compression codes for which the numbers of bits of thecompression codes are less than the allowed maximum number of bits arepreliminary defined for the compression codes illustrated in FIG. 4B. Inthis case, the compression code length of a compression code can beidentified by sequentially identifying the values of the bits of thecompression code from the most significant bit. For the compressioncodes illustrated in FIG. 4B, for example, the allowed maximum number ofbits of the compression codes is defined as three and the value of theleast significant bit of the compression codes for which the numbers ofbits of the compression codes are less than the allows maximum number ofbits is defined as “0”. In this case, when the most significant bit of acompression code is “0”, it is possible to identify that the compressioncode corresponds to compression process #1 and the compression codelength is one. Furthermore, when the most significant bit of acompression code is “1” and the next most significant bit of thecompression code is “0”, it is possible to identify that the compressioncode corresponds to compression process #2 and the compression codelength is two.

Referring back to FIG. 3, the transmitter circuit 11 sequentiallyreceives compressed image data 22 from the compression unit 14 andsequentially transmits transmission data 24 corresponding to thecompressed image data 22 to the receiver circuit 12. The “transmissiondata 24 corresponding to a compressed image data 22” referred to hereinincludes: the compression code included in the compressed image data 22;and a selected one of the compressed image body data included in thecompressed image data 22 and a bit-inverted data obtained by performingdata-bit inversion on the compressed image body data. Accordingly, the“transmission data 24 corresponding to a compressed image data 22” is atleast equivalent to the compressed image data 22. The transmission data24 corresponding to a compressed image data 22 may be identical to thecompressed image data 22, but is not necessarily identical.

More specifically, the transmitter circuit 11 includes a compressioncode length identification section 31, a transmission data comparatorsection 32, a data-bit inversion section 33 and an interface 34.

The compression code length identification section 31 sequentiallyreceives compressed image data 22 from the compression unit 14,identifies the compression code length of each of the receivedcompressed image data 22 and transmits a compression code length signal51 indicative of the identified compression code length to thetransmission data comparator section 32 and the data-bit inversionsection 33.

The transmission data comparator section 32 sequentially receives thecompressed image data 22 from the compression unit 14, compares thetransmission data 24 which has been just previously transmitted to thereceiver circuit 12 over the signal lines 13 a with the compressed imagedata 22 to be currently transmitted to the receiver circuit 12, andgenerates an inversion indication signal 52 on the basis of the resultof the comparison, to instruct whether or not data bit inversion is tobe performed on the compressed image body data. More specifically, thetransmission data comparator section 32 operates as follows:

The transmission data comparator section 32 is configured to, each timewhen a transmission data 24 is transmitted to the receiver circuit 12,store the transmission data 24 or a data equivalent thereto. Thetransmission data 24 itself may be stored in the transmission datacomparator section 32. Alternatively, the combination of the compressedimage data 22 and the inversion indication bit 23 corresponding theretomay be stored in the transmission data comparator section 32; atransmission data 24 transmitted to the receiver circuit 12 can bereproduced from the compressed image data 22 and the inversionindication bit 23 corresponding thereto.

The transmission data comparator section 32 identifies the compressioncode length of the compression code included in the compressed imagedata 22 to be currently transmitted, from the compression code lengthsignal 51 and specifies signal lines 13 a to be used to transmit thecompressed image body data of the compressed image data 22 to becurrently transmitted or the bit-inverted data thereof. When thecompression code length signal 51 indicates that the compression codelength is three, for example, the transmission data comparator section32 specifies that three of the signal lines 13 a are to be used totransmit the compression code and the remaining signal lines 13 a are tobe used to transmit the compressed image body data or the bit-inverteddata.

Furthermore, the transmission data comparator section 32 compares databits of the transmission data 24, which has been transmitted over thesignal lines 13 a to be used to transmit the compressed image body dataof the compressed image data 22 to be currently transmitted or thebit-inverted data thereof, with the compressed image body data of thecompressed image data 22 to be currently transmitted. The transmissiondata comparator section 32 generates the inversion indication signal 52to indicate whether or not data bit inversion is to be performed on thecompressed image body data, in accordance with the result of this datacomparison. The inversion indication signal 52 thus generated istransmitted to the data-bit inversion section 33.

Furthermore, the transmission data comparator section 32 generates theinversion indication bit 23 in accordance with the result of the datacomparison. The inversion indication bit 23 indicates whether or notbit-inversion is performed on the compressed image body data intransmitting the transmission data; the inversion indication bit 23 istransmitted to the receiver circuit 12 as described later.

The data-bit inversion section 33 sequentially receives the compressedimage data 22 from the compression unit 14 and generates transmissiondata 24 to be transmitted to the receiver circuit 12. As describedabove, the compressed image data 22 each include a compression code anda compressed image body data, and processing performed in the data-bitinversion section 33 is different between the compression code and thecompressed image body data. The data-bit inversion section 33incorporates the compression code into the corresponding transmissiondata 24 without bit-inversion, independently of the inversion indicationsignal 52 (that is, not depending on the result of the data comparisonbetween the data which has been just previously transmitted to thereceiver circuit 12 over the signal lines 13 a and the compressed imagedata 22 to be currently transmitted to the receiver circuit 12.) As forthe compressed image body data, on the other hand, the data-bitinversion section 33 is responsive to the inversion indication signal 52for incorporating the compressed image body data into the transmissiondata 24 without bit-inversion, or incorporating the bit-inverted dataobtained by bit-inversion of the compressed image body data into thetransmission data 24.

In this operation, the data-bit inversion section 33 refers to thecompression code length signal 51. The data-bit inversion section 33identifies which part of the compressed image data 22 includes thecompression code and which part of the compressed image data 22 includesthe compressed image body data, from the compression code lengthindicated by the compression code length signal 51. When indicated toperform bit-inversion by the inversion indication signal 52, thedata-bit inversion section 33 generates bit-inverted data by performingbit-inversion on the compressed image body data, and incorporates thebit-inverted data into the transmission data 24, together with thecompression code included in the compressed image data 22. When notindicated to perform bit-inversion, the data-bit inversion section 33incorporates the compressed image body data into the transmission data24, together with the compression code included in the compressed imagedata 22. In this case, the compressed image data 22 itself is used asthe transmission data 24. As a result, a transmission data 24transmitted to the receiver circuit 12 includes a compression code, andalso includes a compressed image body data or the bit-inverted datathereof. As is understood from the above-described discussion, theoperation in which bit-inversion is not performed on the compressioncode effectively reduces the power consumption.

The interface 34 transmits the transmission data 24 received from thedata-bit inversion section 33 to the receiver circuit 12 over the signallines 13 a, and further transmits the inversion indication bit 23received from the transmission data comparator section 32 to thereceiver circuit 12 over the signal line 13 b.

The receiver circuit 12 includes an interface 41, a compression codelength identification section 42 and a data-bit inversion section 43.

The interface 41 receives the transmission data 24 from the transmittercircuit 11 via the signal lines 13 a and receives the inversionindication bit 23 via the signal line 13 b.

The compression code length identification section 42 identifies thecompression code length of each transmission data 24 and generates acompression code length signal 53 indicative of the identifiedcompression code length. Additionally, the compression code lengthidentification section 42 forwards the transmission data 24 to thedata-bit inversion section 43.

The data-bit inversion section 43 reproduces the original compressedimage data 22 from the transmission data 24 and outputs the reproducedcompressed image data 22 as reception compressed image data 25. Morespecifically, the data-bit inversion section 43 identifies which part ofa received transmission data 24 includes the compression code and whichpart of the received transmission data 24 includes the compressed imagebody data or the bit-inverted data, from the compression code lengthindicated by the compression code length signal 53. Furthermore, whenrecognizing that the transmission data 24 includes a compression codeand a bit-inverted data from the inversion indication bit 23 receivedfrom the transmitter circuit 11, the data-bit inversion section 43performs bit-inversion on the bit-inverted data to reproduce theoriginal compressed image body data. In this case, the data-bitinversion section 43 outputs the reception compressed image data 25 sothat the reception compressed image data 25 includes the compressioncode included in the transmission data 24 and the compressed image bodydata thus reproduced. When recognizing that the received transmissiondata 24 includes the compressed image body data of the originalcompressed image data 22, from the inversion indication bit 23 receivedfrom the transmitter circuit 11, on the other hand, the data-bitinversion section 43 incorporates the compressed image body dataincluded in the transmission data 24 into the reception compressed imagedata 25. As for the compression code, the data-bit inversion section 43incorporates the compression code included in the transmission data 24into the reception compressed image data 25 without bit-inversion,independently of the value of the inversion indication bit 23. Thereception compressed image data 25 output in this way from the data-bitinversion section 43 are identical to the corresponding compressed imagedata 22 supplied to the transmitter circuit 11 (as long as there is nocommunication error).

Next, a description is given of an exemplary operation of the image datatransfer system 10 in the present embodiment.

FIG. 5 is a diagram schematically illustrating an exemplary allocationof the signal lines 13 (13 a and 13 b) in transferring compressed imageddata 22 over the image data transfer system 10. In the presentembodiment, transmission data 24 are transmitted over the signal lines13 a and the inversion indication bits 23 are transmitted over thesignal line 13 b. In the example illustrated in FIG. 5, the transmissiondata 24 are 64-bit data and therefore the transmission data 24 aretransmitted with 64 signal lines 13 a. If necessary for distinguishingthe 64 signal lines 13 a from one another, a suffix may be attached tothe reference numeral “13 a”. The signal lines 13 a ₁ to 13 a ₆₄respectively transmit corresponding bits of the transmission data 24.

Since the lengths of the compression codes included in transmission data24 are variable, each of the signal lines 13 a may be allocated to thecompression code or a selected one of the compressed image body data andthe bit-inverted data, depending on the compression code length. Forexample, FIG. 5 illustrates the allocation of the signal lines 13 in thecase where the compression code length is “3”. Three signal lines 13 a ₁to 13 a ₃ are allocated to the compression code and the remaining signallines 13 a ₄ to 13 a ₆₄ are allocated to the compressed image body dataor the bit-inverted data thereof. As thus described, once thecompression code length of the compression code of each transmissiondata 24 is given, it is possible to determine the signal lines 13 a tobe allocated to the compression code and those to be allocated to thecompressed image body data or the bit-inverted data.

In the present embodiment, the transmitter circuit 11 transmits thetransmission data 24 corresponding to the compressed image data 22associated with a specific block as described below:

(1) In relation to the signal line(s) 13 a allocated to the compressioncode, the transmitter circuit 11 transmits the compression code over therelevant signal line(s) 13 a to the receiver circuit 12 withoutperforming bit-inversion.

(2) As for the signal lines 13 a allocated to the compressed image bodydata or the bit-inverted data, the transmitter circuit 11 compares thecompressed image body data with the data which has been transmitted overthe relevant signal lines 13 a and transmits to the receiver circuit 12the compressed image body data itself or the bit-inverted data thereof,depending the data comparison.

(3) Additionally, the transmitter circuit 11 transmits the inversionindication bit 23, which indicates which of the compressed image bodydata itself or the bit-inversion data thereof is transmitted, to thereceiver circuit 12 over the signal line 13 b.

When the compression code length is three as illustrated in FIG. 5, thesignal lines 13 a ₁ to 13 a ₃ are allocated to the compression code andthe signal lines 13 a ₄ to 13 a ₆₄ are allocated to the compressed imagebody data or the bit-inverted data thereof. In this case, the respectivebits of the compressed image body data are compared with thecorresponding bits of the data which has been just previouslytransmitted over the signal lines 13 a ₄ to 13 a ₆₄. The transmittercircuit 11 determines which of the compressed image body data itself andthe bit-inverted data thereof is to be transmitted, depending on theresult of the data comparison. Most typically, when more than half ofthe bits of the compressed image body data are inverted from thecorresponding bits of the data which has been just previouslytransmitted over the signal lines 13 a ₄ to 13 a ₆₄, the bit-inverteddata is incorporated into the transmission data 24. Otherwise, thecompressed image body data is incorporated into the transmission data 24without bit-inversion.

The receiver circuit 12 reproduces the original compressed image data 22from the transmission data 24 received from the transmitter circuit 11,referring to the inversion indication bit 23. The original compressedimage data 22 thus reproduced is output from the receiver circuit 12 asthe reception compressed image data 25. More specifically, whenrecognizing from the inversion indication bit 23 that the compressedimage body data is transmitted without data-bit inversion, the receivercircuit 12 incorporates the compression code and compressed image bodydata included in the transmission data 24 into the reception compressedimage data 25 without performing data-bit inversion and outputs thereception compressed image data 25 thus generated. When recognizing fromthe inversion indication bit 23 that the bit-inverted data of thecompressed image body data is transmitted, on the other hand, thereceiver circuit 12 reproduces the original compressed image body databy performing data-bit inversion on the bit-inverted data, incorporatesthe compression code included in the transmission data 24 and thecompressed image body data thus reproduced, into the receptioncompressed image data 25, and outputs the reception compressed imagedata 25 thus generated.

FIG. 6 illustrates one example of transmission of a transmission data24. Illustrated in FIG. 6 is the case where the compression code lengthof the transmission data 24 which has been just previously transmittedis three and the compression code length of the compressed image data 22to be currently transmitted is also three. In FIG. 6, the legend“D_(CODE)[i]” denotes a bit of the compression code, and the legend“D_(BODY)[i]” denotes a bit of the compressed image body data. In thefollowing, a discussion is given of the case where, in just previoustransmission of the transmission data 24, the bits D_(CODE)[0] toD_(CODE)[2] of the compression code have been transmitted over thesignal lines 13 a ₁ to 13 a ₃ and the bits D_(BODY)[0] to D_(BODY)[60]of the compressed image body data have been transmitted over the signallines 13 a ₄ to 13 a ₆₄. It should be noted that the bit D_(CODE[i])indicates a higher-order bit of the compression code as the parameter“i” is decreased.

When a compressed image data 22 to be currently transmitted is suppliedto the transmitter circuit 11, the compression code lengthidentification section 31 of the transmitter circuit 11 identifies thecompression code length of the compressed image data 22. In the presentembodiment, the compression code is defined as illustrated in FIG. 4B,and the compression code length identification section 31 identifies thecompression code length by sequentially identifying the values of thebits of the compression code from the most significant bit. It should benoted that, in the definition of the compression code illustrated inFIG. 4B, the allowed maximum compression code length is three and thevalue of the least significant bit of the compression code for which thenumber of bits is less than the allowed maximum compression code lengthis “0”. The compression code length identification section 31 identifiesthat the compression code length is three, since the most significantbit D_(CODE)[0] and the next most significant bit D_(CODE)[1] of thecompression code are both “1”. The compression code length signal 51 istransmitted to the transmission data comparator section 32 and thedata-bit inversion section 33 to indicate the identified compressioncode length.

The transmission data comparator section 32 identifies the compressioncode length of the compressed image data 22 to be currently transmitted,on the basis of the compression code length signal 51, and specifies thesignal lines 13 a to be used for transmitting the compressed image bodydata or the bit-inverted data thereof, with respect to the transmissiondata 24 corresponding to the compressed image data 22 to be currentlytransmitted, on the basis of the identified compression code length. Inthe example illustrated in FIG. 6, since the compression code length ofthe compressed image data 22 to be currently transmitted is three, thetransmission data comparator section 32 specifies the signal lines 13 a₄ to 13 a ₆₄ as the signal lines to be used for transmitting thecompressed image body data or the bit-inversion data thereof, withrespect to the transmission of the corresponding transmission data 24.

Furthermore, the transmission data comparator section 32 compares therespective bits of the compressed image body data of the compressedimage data 22 to be currently transmitted, with the corresponding bitsof the transmission data 24 which has been just previously transmittedover the signal lines 13 _(a4) to 13 a ₆₄. The transmission datacomparator section 32 generates the inversion indication signal 52 toindicate whether or not data-bit inversion is to be performed on thecompressed image body data, in accordance with the result of this datacomparison. The inversion indication signal 52 thus generated istransmitted to the data-bit inversion section 33. Additionally, thetransmission data comparator section 32 transmits to the receivercircuit 12 the inversion indication bit 23, which indicates whether ornot data-bit inversion is performed on the compressed image body data ofthe compressed image data 22 to be currently transmitted, via theinterface 34.

The data-bit inversion section 33 identifies which part of thecompressed image data 22 to be currently transmitted incorporates thecompression code and which part of the same incorporates the compressedimage body data from the compression code length indicated by thecompression code length signal 51 received from the compression codelength identification section 31. Furthermore, in response to theinversion indication signal 52, the data-bit inversion section 33incorporates the compressed image body data into the transmission data24 without performing data-bit inversion, or incorporates thebit-inverted data obtained through data bit-inversion of the compressedimage body data into the transmission data 24. As for the compressioncode, on the other hand, the data-bit inversion section 33 incorporatesthe compression code into the transmission data 24 to be transmitted tothe receiver circuit 12, without performing data-bit inversion,independently of the inversion indication signal 52.

In the example illustrated in FIG. 6, more than half of the bits of thecompressed image body data of the compressed image data 22 to becurrently transmitted are inverted from the corresponding bits of thetransmission data 24 which has been just previously transmitted over thesignal lines 13 a ₄ to 13 a ₆₄. Accordingly, the transmission datacomparator section 32 determines that data-bit inversion is to beperformed on the compressed image body data of the compressed image data22 to be currently transmitted. The transmission data comparator section32 instructs the data-bit inversion section 33 to perform data-bitinversion on the compressed image body data of the compressed image data22 to be currently transmitted by using the inversion indication signal52, and notifies the receiver circuit 12 of the fact that data-bitinversion is performed on the compressed image body data by using theinversion indication bit 23. The data-bit inversion section 33 transmitsthe compression code of the compressed image data 22 to the receivercircuit 12 over the signal lines 13 a ₁ to 13 a ₃ without performingdata-bit inversion and also transmits the bit-inverted data obtained byperforming data-bit inversion on the compressed image body data to thereceiver circuit 12 over the signal lines 13 a ₄ to 13 a ₆₄.

It should be noted that, although the compression code length of thecompressed image data 22 to be currently transmitted is identical tothat of the transmission data 24 which has been just previouslytransmitted in the example illustrated in FIG. 6, the compression codelengths may be different from each other. In this case, one or more bitsof the compressed image body data of the compressed image data 22 may becompared with the corresponding bit(s) of the compression code of thetransmission data 24 which has been just previously transmitted. FIG. 7illustrates an operation in such a case.

Illustrated in FIG. 7 is an example in which the compression code lengthof the transmission data 24 which has been just previously transmittedis three and the compression code length of the compressed image data 22to be currently transmitted is two. In the just previous transmission ofthe transmission data 24, the bits D_(CODE)[0] -D_(CODE)[2] of thecompression code are transmitted over the signal lines 13 a ₁ to 13 a ₃,and the bits D_(BODY)[0]-D_(BODY)[60] of the compressed image body dataare transmitted over the signal lines 13 a ₄ to 13 a ₆₄.

Since the compression code length of the compressed image data 22 to becurrently transmitted is two, the transmission data comparator section32 specifies the signal lines 13 a ₃ to 13 a ₆₄ to be used fortransmitting the compressed image body data or bit-inverted data of thecorresponding transmission data 24. Furthermore, the transmission datacomparator section 32 compares the respective bits of the compressedimage body data of the compressed image data 22 to be currentlytransmitted with the corresponding bits of the transmission data 24which has been just previously transmitted over the signal lines 13 a ₃to 13 a ₆₄. In the case illustrated in FIG. 7, the most significant bitD_(BODY)[0] of the compressed image body data of the compressed imagedata 22 to be currently transmitted is compared with the leastsignificant bit D_(CODE)[2] of the compression code of the transmissiondata 24 which has been just previously transmitted over the signal line13 a ₃, since the signal line 13 a ₃ is allocated to the mostsignificant bit D_(BODY)[0] of the compressed image body data. Also inthis case, the transmission data comparator section 32 generates theinversion indication signal 52, which indicates whether or not data-bitinversion is to be performed on the compressed image body data, inaccordance with the result of this data comparison.

As thus described, in the present embodiment, the compression code of acompressed image data is transmitted without data-bit inversion, whilethe compressed image body data, which includes bits of the compressedimage data other than the compression code, are compared with the datawhich has been just previously transmitted to determine which of thecompressed image body data itself or the bit-inverted data thereof is tobe transmitted, in accordance with the result of the data comparison.This effectively reduces the power consumption in transmitting thecompressed image data.

It should be noted that, although the above-described embodiment isdirected to the case where the compression code length is variable, thetechnique of the present disclosure is applicable to the case where thecompression code length is fixed. FIG. 8 is a block diagram illustratingan exemplary configuration of an image data transfer system 10A in anembodiment in which the compression code length is fixed.

The image data transfer system 10A illustrated in FIG. 8 is configuredsimilarly to the image data transfer system 10 illustrated in FIG. 3.The difference is that, in the image data transfer system 10Aillustrated in FIG. 8, the compression code length identificationsection 31 is removed from the transmitter circuit 11 and thecompression code length identification section 42 is removed from thereceiver circuit 12.

The operation of the image data transfer system 10A illustrated in FIG.8 is almost similar to that of the image data transfer system 10illustrated in FIG. 3, except for that identification of the compressioncode length is not performed. It is not necessary to identify thecompression code length upon reception of the compressed image data 22,since the compression code length is fixed.

More specifically, the transmission data comparator section 32 in thetransmitter circuit 11 compares the compressed image body data of thecompressed image data 22 to be currently transmitted with the data whichhas been just previously transmitted over the signal lines 13 a to beused to transmit the compressed image body data or the bit-inverted datathereof for the compressed image data 22 to be currently transmitted.The transmission data comparator section 32 generates the inversionindication signal 52 to indicate whether data-bit inversion is to beperformed on the compressed image body data, in accordance with theresult of this data comparison. The generated inversion indicationsignal 52 is transmitted to the data-bit inversion section 33.Additionally, the transmission data comparator section 32 generates theinversion indication bit 23 in accordance with the result of the datacomparison.

The data-bit inversion section 33 sequentially receives compressed imagedata 22 from the compression unit 14 and generates transmission data 24to be transmitted to the receiver circuit 12. As described above, thecompressed image data 22 each include a compression code and acompressed image body data, and the processing performed in the data-bitinversion section 33 is different between the compression code and thecompressed image body data. The data-bit inversion section 33incorporates the compression code into the transmission data 24 withoutperforming data-bit inversion independently of the inversion indicationsignal 52 (that is, independently of the result of the data comparisonbetween the compressed image data 22 to be currently transmitted to thereceiver circuit 12 with the data which has been just previouslytransmitted to the receiver circuit 12 over the signal lines 13 a.) Onthe other hand, the data-bit inversion section 33 is responsive to theinversion indication signal 52 for incorporating the compressed imagebody data into the transmission data 24 without performing data-bitinversion or incorporating the bit-inverted data obtained by performingdata-bit inversion on the compressed image body data into thetransmission data 24. The transmission data 24 thus generated istransmitted to the receiver circuit 12.

The data-bit inversion section 43 in the receiver circuit 12 reproducesthe original compressed image data 22 from the transmission data 24, andoutputs the reproduced compressed image data 22 as the receptioncompressed image data 25. More specifically, when recognizing that thetransmission data 24 includes the compression code and the bit-inverteddata on the basis of the inversion indication bit 23 received from thetransmitter circuit 11, the data-bit inversion section 43 performsdata-bit inversion on the bit-inverted data to reproduce the originalcompressed image body data. The data-bit inversion section 43 outputsthe reception compressed image data 25 which incorporates thecompression code included in the transmission data 24 and the reproducedcompressed image body data. When recognizing that the transmission data24 is identical to the original compressed image data 22 on the basis ofthe inversion indication bit 23 received from the transmitter circuit11, on the other hand, the data-bit inversion section 43 outputs thereceived transmission data 24 as the reception compressed image data 25without performing data-bit inversion.

The image data transfer system (10, 10A) of the present embodiment isapplicable to various devices and systems in which compressed image dataare transferred. In one example, the image data transfer system of thepresent embodiment may be used for transferring compressed image datawithin a display driver which drives a display panel.

FIG. 9 is a block diagram illustrating an exemplary configuration of adisplay device 70 in which the image data transfer system (10, 10A) ofthe present embodiment is used to transfer compressed image data withina display driver IC 71. The display driver IC 71 is configured toreceive image data 21 from a timing controller 72 and drive a displaypanel 73 (e.g. a liquid crystal display panel) to display an imagecorresponding to the image data 21.

The display device 70 illustrated in FIG. 9 is configured so that thedisplay driver IC 71 generates compressed image data 22 by performingimage compression on the image data 21 and distributedly stores thecompressed image data 22 into a plurality of storage units, morespecifically, a plurality of RAMs (random access memories). Suchconfiguration aims at reducing the total capacity of the storage units(RAMs) integrated in the display driver IC 71. A RAM may be integratedin a display driver IC to temporarily store image data; however suchconfiguration suffers from a problem that the RAM occupies a large areain the display driver IC. The configuration of the display driver 71illustrated in FIG. 9 effectively reduces the total capacity of theRAMs, since the compressed image data 22 are stored in the RAMs.

More specifically, the display driver IC 71 includes a logic circuit 81,left RAMs 82L, right RAMs 82R, and a source driver circuit 83. The logiccircuit 81, the left RAMs 82L, the right RAMs 82R, and the source drivercircuit 83 are monolithically integrated in the display driver IC 71. Inother words, the logic circuit 81, the left RAMs 82L, the right RAMs82R, and the source driver circuit 83 are integrated in the samesemiconductor chip. The logic circuit 81 is connected to the left RAMs82L via left buses 84L and 85L and is also connected to the right RAMs82L via right buses 84R and 85R. Each of the left buses 84L, 85L, theright buses 84R and 85R, which includes a plurality of signal lines,corresponds to the signal lines 13 in the above-described embodiment.

The logic circuit 81 includes a compression circuit 81 a, transmittercircuits 11R, 11L, receiver circuits 12R, 12L and a decompressioncircuit 81 b. The transmitter circuits 11R and 11L of the logic circuit81 are configured similarly to the transmitter circuit 11 of theabove-described embodiment and operate in a similar manner to thetransmitter circuit 11. The receiver circuits 12R and 12L of the logiccircuit 81 are configured similarly to the receiver circuit 12 of theabove-described embodiment and operate in a similar manner to thereceiver circuit 12.

The compression circuit 81 a, which corresponds to the compression unit14 in the above-described embodiment, is configure to sequentiallygenerate compression image data 22 by performing block compression onthe image data 21 sequentially supplied thereto. When performing imagecompression on the image data 21 associated with each block, thecompression circuit 81 a selects a desired one of a plurality ofcompression processes on the basis of the characteristics of the imagedata 21 associated with each block and generates the correspondingcompressed image data 22 by performing the selected compression processon the image data 21 associated with each block.

The transmitter circuit 11L transmits to the left RAMs 82L data to bestored in the left RAMs 82L selected from the compressed image data 22generated by the compression circuit 81 a via the left bus 84L.Similarly, the transmission circuit 11R transmits to the right RAMs 82Rdata to be stored in the right RAMs 82R selected from the compressedimage data 22 generated by the compression circuit 81 a via the rightbus 84R.

The receiver circuit 12L receives the compressed image data 22 stored inthe left RAMs 82L via the left bus 85L and outputs the receivedcompressed image data 22 as the reception compressed image data 25.Similarly, the receiver circuit 12R receives the compressed image data22 stored in the right RAMs 82R via the right bus 85R and outputs thereceived compressed image data 22 as the reception compressed image data25.

The decompression circuit 81 b performs a decompression process on thereception compressed image data 25 received from the receiver circuits12R and 12L to generate decompressed image data 86.

The left RAMs 82L and the right RAMs 82R store therein the compressedimage data 22 received from the logic circuit 81. Each of the left RAMs82L and the right RAMs 82R includes a transmitter circuit 11 and areceiver circuit 12. The transmitter circuits 11 of the left RAMs 82Land the right RAMs 82R are configured similarly to the transmittercircuit 11 of the above-described embodiment and operate in a similarmanner. The receiver circuits 12 of the left RAMs 82L and the right RAMs82R are configured similarly to the receiver circuit 12 of theabove-described embodiment and operate in a similar manner. The leftRAMs 82L each receive the compressed image data 22 from the transmittercircuit 11L of the logic circuit 81 by using the receiver circuit 12provided therein and stores the compressed image data 22 thus received.Similarly, the right RAMs 82R each receive the compressed image data 22from the transmitter circuit 11R of the logic circuit 81 by using thereceiver circuit 12 provided therein and stores the compressed imagedata 22 thus received. Additionally, the left RAMs 82L each transmit thecompressed image data 22 stored therein to the receiver circuit 12L ofthe logic circuit 81 by using the transmitter circuit 11 providedtherein. Similarly, the right RAMs 82R each transmit the compressedimage data 22 stored therein to the receiver circuit 12R of the logiccircuit 81 by using the transmitter circuit 11 provided therein.

The source driver circuit 83 drives the source lines (also referred toas data lines or signal lines) in response to the decompressed imagedata 86 received from the decompression circuit 81 b of the logiccircuit 81.

Schematically, the display device 70 illustrated in FIG. 9 operates asfollows: When image data 21 are supplied to the display driver IC 71from the timing controller 72, image compression is performed on theimage data 21 by the compression circuit 81 a of the logic circuit 81 togenerate compressed image data 22. The compressed image data 22 aretransmitted to the left RAMs 82L and the right RAMs 82R by thetransmitter circuits 11L and 11R and distributedly stored in the leftRAMs 82L and the right RAMs 82R.

The display panel 73 is driven in response to the compressed image data22 stored in the left RAMs 82L and the right RAMs 82R. The compressedimage data 22 stored in the left RAMs 82L and the right RAMs 82R aretransmitted to the logic circuit 81 and then decompressed by thedecompression circuit 81 b to generate decompressed image data 86. Thesource lines of the display panel 73 are driven by the source drivercircuit 83 in response to the decompressed image data 86.

The image data transfer system (10, 10A) of the present embodiment isalso applicable to various systems in which compressed image data aretransferred between two semiconductor ICs. In one example, the imagedata transfer system (10, 10A) is applicable to transfer of compressedimage data from a timing controller IC to a display driver IC whichdrives a display panel. In general, image data used to display a displaypanel have a large size and therefore a large amount of power isconsumed in a system structure in which image data are transferred froma timing controller to a display driver IC; however, the systemstructure in which compressed image data obtained by performing imagecompressed on image data are transferred from the timing controller ICto the display driver IC effectively reduces the data amount of thetransfer data to thereby reduce the power consumption.

FIG. 10 is a block diagram illustrating an exemplary configuration of adisplay device 90 in which the image data transfer system (10, 10A) ofthe present embodiment is used to transfer compressed image data from atiming controller IC to display driver ICs. The display device 90 of thepresent embodiment includes a timing controller IC 91, a plurality ofdisplay driver ICs 92 and a display panel 93 (for example, a liquidcrystal display panel). The display driver ICs 92 are connected to thetiming controller IC 91 via a bus 94. The bus 94, which includes aplurality of signal lines, corresponds to the signal lines 13 of theabove-described embodiment.

The timing controller IC 91 includes a compression circuit 91 a and atransmitter circuit 11. The compression circuit 91 a, which correspondsto the compression unit 14 of the above-described embodiment, isconfigured to perform block compression on the image data 21sequentially supplied thereto generate decompressed image data 22. Whencompressing the image data 21 associated with each block, thecompression circuit 91 a selects a desired one of a plurality ofcompression processes in response to the characteristics of the imagedata 21 associated with each block, and generates compressed image data22 by performing the selected compression process on the image data 21associated with each block. The transmitter circuit 11 transmits thecompressed image data 22 to the display driver ICs 92.

Each of the display driver ICs 92 includes a receiver circuit 12, adecompression circuit 92 a and a source driver circuit 92 b. Thereceiver circuit 12 receives the compressed image data 22 from thetiming controller IC 91 and outputs the received compressed image data22 as reception compressed image data to the decompression circuit 92 a.The decompression circuit 92 a decompresses the reception compressedimage data received from the receiver circuit 12 to generatedecompressed image data. The source driver circuit 92 b drives thesource lines of the display panel 93 in response to the decompressedimage data received from the decompression circuit 92 a.

Although various embodiments of the present disclosure have beenspecifically described in the above, the present disclosure must not beconstrued as being limited to the above-described embodiments. A personskilled in the art would appreciate that the present disclosure may beimplemented with various modifications.

For example, the transmitter circuit 11 is configured to incorporate thecompression code of each compressed image data 22 into the transmissiondata 24 without change in the above-described embodiments, thetransmitter circuit 11 may be instead configured to incorporate into thetransmission data 24 a data equivalent to the compression code, forexample, an arithmetic operation data obtained by performing apredetermined arithmetic operation on the compression code. When anarithmetic operation data equivalent to the compression code of thecompressed image data 22 is incorporated to the transmission data 24,the arithmetic operation data is generated with a predeterminedarithmetic operation which does not depend on the result of the datacomparison of the bits of the compressed image body data with data whichhas been just previously transmitted over the signal lines 13 allocatedto the compressed image body data or the bit-inverted data. For example,bit-inversion may be unconditionally performed on the compression codesof all of the compressed image data 22. In this case, the logicalarithmetic data obtained through the bit-inversion may be incorporatedinto the transmission data 24.

Also, although the receiver circuit 12 is configured to incorporate thecompression code included in each transmission data 24 into thereception compressed image data 25 without change in the above-describedembodiments, the receiver circuit 12 may be configured to incorporateinto the reception compressed image data 25 a data equivalent to thecompression code included in each transmission data 24 (or thearithmetic operation data equivalent to the compression code included inthe compressed image data 22), for example, an arithmetic operation dataobtained by performing a predetermined arithmetic operation on thecompression code. When an arithmetic operation data equivalent to thecompression code of the transmission data 24 is incorporated in thereception compressed image data 25, the arithmetic operation data isgenerated through a predetermined arithmetic operation which does notdepend on the inversion indication bit 23. When an arithmetic operationdata equivalent to the compression code of a compressed image data 22 isincorporated into the corresponding transmission data 24, the arithmeticoperation data is generated through a predetermined arithmetic operationwhich does not depends on the result of data comparison of thecompressed image body data of the compressed image data 22 with the datawhich has been just previously transmitted over the signal lines 13 aallocated to the compressed image body data or the bit-inverted datathereof. Especially, when each transmission data 24 includes anarithmetic operation data equivalent to the compression code included inthe compressed image data 22, the original compression code reproducedby the arithmetic operation data may be incorporated into the receptioncompressed image data 25.

It is apparent that the present disclosure is not limited to theabove-described embodiments, which may be modified and changed withoutdeparting from the scope of the disclosure.

What is claimed is:
 1. An image data transfer system, comprising: areceiver; and a transmitter configured to sequentially receivecompressed image data, and to sequentially transmit transmission datacorresponding to the compressed image data to the receiver, wherein eachof the compressed image data is generated through a selected compressionprocess selected from a plurality of compression processes and includesa compression code indicating the selected compression process and acompressed image body data, wherein each of the transmission dataincludes the compression code included in the corresponding compressedimage data and a selected one of the compressed image body data of thecorresponding compressed image data and a bit-inverted data obtainedthrough bit-inversion on the compressed image body data of thecorresponding compressed image data, and wherein the transmitter isconfigured to, when transmitting a specific one of the transmission datacorresponding to a specific one of the compressed image data, performdata comparison of bits of the compressed image body data of thespecific compressed image data with bits of a previous one of thetransmission data which has just previously transmitted before thespecific transmission data over signal lines allocated to the compressedimage body data of the specific compressed image data or thebit-inverted data, incorporate the compressed image body data of thespecific compressed image data or the bit-inverted data correspondingthereto into the specific transmission data, in response to the resultof the data comparison, and incorporate the compression code of thespecific compressed image data into the specific transmission dataindependently of the result of the data comparison.
 2. The image datatransfer system according to claim 1, wherein transmitting the specifictransmission data to the receiver comprises: transmitting an inversionindication bit indicating which of the compressed image body data of thespecific compressed image data and the bit-inverted data correspondingthereto is transmitted to the receiver, wherein the receiver isconfigured to sequentially receive the transmission data and outputreception compressed image data respectively corresponding to thetransmission data, and wherein, when receiving the specific transmissiondata from the transmitter, the receiver is configured to refer to theinversion indication bit, incorporate the compressed image body dataincluded in the specific transmission data into the reception compressedimage data corresponding to the specific transmission data, when thespecific transmission data includes the compressed image body data ofthe specific compressed image data, incorporate data obtained byperforming bit-inversion on the bit-inverted data included in thespecific transmission data into the reception compressed image datacorresponding to the specific transmission data, when the specifictransmission data includes the bit-inversion data of the compressedimage body data of the specific compressed image data, and incorporatethe compression code included in the specific transmission data into thereception compressed image data corresponding to the specifictransmission data, independently of the inversion indication bit.
 3. Theimage data transfer system according to claim 1, wherein numbers of bitsof the compression codes of the compressed image data are variable inresponse to the selection of the plurality of compression processes,wherein the transmitter includes: a first compression code lengthidentification section configured to identify the number of bits of thecompression code of the specific compressed image data and output afirst compression code length signal indicating the identified number ofbits of the compression code of the specific compressed image data; atransmission data comparator section to identify the signal linesallocated to the compressed image body data of the specific compressedimage data or the bit-inverted data corresponding thereto based on thefirst compression code length signal, and performs the data comparisonof the bits of the compressed image body data of the specific compressedimage data with the bits of the previous transmission data which havebeen transmitted over the signal lines; and a first data-bit inversionsection configured to incorporate the compressed image body data of thespecific compressed image data or the bit-inverted data correspondingthereto in response to the result of the data comparison and the firstcompression code length signal, and incorporate the compression code ofthe specific compressed image data into the specific transmission dataindependently of the result of the data comparison.
 4. The image datatransfer system according to claim 2, wherein the receiver includes: asecond compression code length identification section configured toidentify the number of bits of the compression code included in thespecific transmission data and output a second compression code lengthsignal indicating the identified number of bits of the compression codeincluded in the specific transmission data; and a second data-bitinversion section configured to incorporate the compressed image bodydata included in the specific transmission data into the receptioncompressed image data corresponding to the specific transmission data inresponse to the inversion indication bit and the second compression codelength signal, when the specific transmission data includes thecompressed image body data of the specific compressed image data,incorporate the bit-inverted data included in the specific transmissiondata into the reception compressed image data corresponding to thespecific transmission data in response to the inversion indication bitand the second compression code length data, when the specifictransmission data includes the bit-inverted data of the specificcompressed image data, and incorporate the compression code included inthe specific transmission data into the reception compressed image datacorresponding to the specific transmission data, independently of theinversion indication bit.
 5. The image data transfer system according toclaim 1, further comprising: a compression unit configured tosequentially receive image data, select the selected compression processfor each of the image data from the plurality of compression processesin response to characteristics of each of the image data, and generatethe compressed image data by performing the selected compression processeach of the image data.
 6. A transmitter circuit configured tosequentially receive compressed image data and sequentially transmittransmission data corresponding to the compressed image data, whereineach of the compressed image data is generated through a selectedcompression process selected from a plurality of compression processesand includes a compression code indicating the selected compressionprocess and a compressed image body data, and wherein each of thetransmission data includes the compression code included in thecorresponding compressed image data and selected one of the compressedimage body data of the corresponding compressed image data and abit-inverted data obtained through bit-inversion on the compressed imagebody data of the corresponding compressed image data, a transmissiondata comparator section configured to, in transmitting a specific one ofthe transmission data corresponding to a specific one of the compressedimage data, perform data comparison of bits of the compressed image bodydata of the specific compressed image data with bits of a previous oneof the transmission data which has just previously transmitted beforethe specific transmission data over signal lines allocated to thecompressed image body data of the specific compressed image data or thebit-inverted data corresponding thereto; and a data-bit inversionsection configured to incorporate the compressed image body data of thespecific compressed image data or the bit-inverted data correspondingthereto into the specific transmission data, in response to the resultof the data comparison and incorporate the compression code of thespecific compressed image data into the specific transmission dataindependently of the result of the data comparison.
 7. The transmittercircuit according to claim 6, further comprising a first compressioncode length identification section configured to identify the number ofbits of the compression code of the specific compressed image data andoutput a first compression code length signal indicating the identifiednumber of bits of the compression code of the specific compressed imagedata, wherein the transmission data comparator section is configured toidentify the signal lines allocated to the compressed image body data ofthe specific compressed image data or the bit-inverted datacorresponding thereto based on the first compression code length signal,and performs the data comparison of the bits of the compressed imagebody data of the specific compressed image data with the bits of theprevious transmission data which have been transmitted over the signallines.
 8. A receiver circuit comprising: an interface configured toexternally and sequentially receive transmission data generated fromcompressed image data and inversion indication bits associatedtherewith; and a data-bit inversion section configured to sequentiallyreceive the transmission data and output reception compressed image datarespectively corresponding to the transmission data in response to theinversion indication bits, wherein each of the compressed image data isgenerated through a selected compression process selected from aplurality of compression processes and includes a compression codeindicating the selected compression process and a compressed image bodydata, wherein each of the transmission data includes the compressioncode included in the corresponding compressed image data and selectedone of the compressed image body data of the corresponding compressedimage data and a bit-inverted data obtained through bit-inversion on thecompressed image body data of the corresponding compressed image data,wherein each of the inversion indication bits indicates which of thecompressed image body data of the corresponding compressed image dataand the bit-inverted data corresponding thereto is included in thecorresponding transmission data, wherein the data-bit inversion sectionis configured to, in receiving a specific one of the transmission data,refer to the inversion indication bit associated with the specifictransmission data, incorporate the compressed image body data includedin the specific transmission data into the reception compressed imagedata corresponding to the specific transmission data when the specifictransmission data includes the compressed image body data of thespecific compressed image data, incorporate data obtained by performingbit-inversion on the bit-inverted data included in the specifictransmission data into the reception compressed image data correspondingto the specific transmission data, when the specific transmission dataincludes the bit-inversion data of the compressed image body data of thespecific compressed image data, and incorporate the compression codeincluded in the specific transmission data into the reception compressedimage data corresponding to the specific transmission data,independently of the corresponding inversion indication bit.
 9. Thereceiver circuit according to claim 8, further comprising: a secondcompression code length identification section configured to identifythe number of bits of the compression code included in the specifictransmission data and output a second compression code length signalindicating the identified number of bits of the compression codeincluded in the specific transmission data; and wherein the data-bitinversion section is configured to identify, with respect to thespecific transmission data, a first part incorporating the compressioncode of the corresponding compressed image data, and a second partincorporating the compressed image body data of the correspondingcompressed image data or the bit-inverted data corresponding thereto,based on the second compression code length signal.